"Declared plans by some states to inflict a military strike on Syria are an undisguised challenge to the key provisions of the UN charter and other norms of international law," Russian Deputy Foreign Minister Gennady Gatilov said.

Russia on Wednesday stressed that it was premature to mull any reaction by the United Nations Security Council to an alleged chemical attack near Damascus before the UN team inspecting the site releases its findings.

"At this stage it is necessary to use political and diplomatic instruments to the maximum, first and foremost by letting the UN experts inspecting possible chemical weapons use in Syria complete their mandate and report the results to the UN Security Council," Gatilov said.

Russia, which has supported the Damascus regime throughout the two-and-a-half-year conflict, is widely expected to block any Security Council action aimed at punishing Syrian President Bashar al-Assad.